3 Theoretical description of reaction mechanisms: reaction pathways and electronic structure rearrangements

2001 ◽  
Vol 97 (1) ◽  
pp. 61-90 ◽  
Author(s):  
Peter B. Karadakov
Keyword(s):  
Electronic Structure ◽  
Reaction Mechanisms ◽  
Theoretical Description ◽  
Reaction Pathways

scholarly journals Gasification Pathways and Reaction Mechanisms of Primary Alcohols in Supercritical Water

2019 ◽  
Author(s):  
Brian Pinkard ◽  
John Kramlich ◽  
Igor V. Novosselov
Keyword(s):  
Free Radical ◽  
Supercritical Water ◽  
Reaction Mechanisms ◽  
Radical Reaction ◽  
Water Environment ◽  
Waste To Energy ◽  
Reaction Pathways ◽  
Free Radical Reaction ◽  
Reaction Products ◽  
Primary Alcohols

<div> <p></p><p>Supercritical water gasification is a promising waste-to-energy technology with the ability to convert aqueous and/or heterogeneous organic feedstocks to high-value gaseous products. Reaction behavior of complex molecules in supercritical water can be inferred through knowledge of the reaction pathways of model compounds in supercritical water. In this study methanol, ethanol, and isopropyl alcohol are gasified in a continuous supercritical water reactor at temperatures between 500 and 560 °C, and for residence times between 3 and 8 s. <i>In situ</i> Raman spectroscopy is used to rapidly identify and quantify reaction products. The results suggest the dominance of chain-branching, free radical reaction mechanisms that are responsible for decomposing primary alcohols in the supercritical water environment. The presence of a catalytic surface is proposed to be highly significant for initiating radical reactions. Global reaction pathways are proposed, and mechanisms for free radical reaction initiation, propagation, and termination are discussed in light of these and previously published experimental results.</p><br><p></p></div>

scholarly journals Gasification Pathways and Reaction Mechanisms of Primary Alcohols in Supercritical Water

2019 ◽  
Author(s):  
Brian Pinkard ◽  
John Kramlich ◽  
Igor V. Novosselov
Keyword(s):  
Free Radical ◽  
Supercritical Water ◽  
Reaction Mechanisms ◽  
Radical Reaction ◽  
Water Environment ◽  
Waste To Energy ◽  
Reaction Pathways ◽  
Free Radical Reaction ◽  
Reaction Products ◽  
Primary Alcohols

<div> <p></p><p>Supercritical water gasification is a promising waste-to-energy technology with the ability to convert aqueous and/or heterogeneous organic feedstocks to high-value gaseous products. Reaction behavior of complex molecules in supercritical water can be inferred through knowledge of the reaction pathways of model compounds in supercritical water. In this study methanol, ethanol, and isopropyl alcohol are gasified in a continuous supercritical water reactor at temperatures between 500 and 560 °C, and for residence times between 3 and 8 s. <i>In situ</i> Raman spectroscopy is used to rapidly identify and quantify reaction products. The results suggest the dominance of chain-branching, free radical reaction mechanisms that are responsible for decomposing primary alcohols in the supercritical water environment. The presence of a catalytic surface is proposed to be highly significant for initiating radical reactions. Global reaction pathways are proposed, and mechanisms for free radical reaction initiation, propagation, and termination are discussed in light of these and previously published experimental results.</p><br><p></p></div>

scholarly journals Revisiting Catalytic Cycles: A Broader View Through the Energy Span Model

2020 ◽  
Author(s):  
Diego Garay-Ruiz ◽  
Carles Bo
Keyword(s):  
Catalytic Reaction ◽  
Reaction Mechanisms ◽  
Computational Study ◽  
Reaction Network ◽  
Co2 Hydrogenation ◽  
Level Of Detail ◽  
Reaction Pathways ◽  
Catalytic Systems ◽  
Computational Code ◽  
Catalytic Cycles

<div><div><div><p>The computational study of catalytic processes allows discovering really intricate and detailed reaction mechanisms that involve many species and transformations. This increasing level of detail can even result detrimental when drawing conclusions from the computed mechanism, as many co-existing reaction pathways can be in close com- petence. Here we present a reaction network-based implementation of the energy span model in the form of a computational code, gTOFfee, capable of dealing with any user-specified reaction network. This approach, compared to microkinetic simulations, enables a much easier and straightforward analysis of the performance of any catalytic reaction network. In this communication, we will go through the foundations and appli- cability of the underlying model, and will tackle the application to two relevant catalytic systems: homogeneous Co-mediated propene hydroformylation and heterogeneous CO2 hydrogenation over Cu(111).</p></div></div></div>

scholarly journals Study of Interaction between Tigecycline and Sulbactam

2019 ◽  
pp. 1-9
Author(s):  
Hakan Sezgin Sayiner ◽  
Fatma Genç ◽  
Fatma Kandemirli
Keyword(s):  
Electronic Structure ◽  
Reaction Mechanism ◽  
Peripheral Neuropathy ◽  
Drug Interactions ◽  
Reaction Mechanisms ◽  
Bond Formation ◽  
Therapeutic Drug ◽  
Energetic Condition ◽  
Biochemical Systems ◽  
Semi Empirical

Drug interactions can have desired, reduced or unwanted effects. The probability of interactions increases with the number of drugs taken. Side effects or therapeutic drug interactions can increase or decrease the effects of one or two drugs. Failure may result from clinically meaningful interactions. Clinicians rarely use foreseeable drug-drug interactions to produce the desired therapeutic effect. For example, when we consider two drugs each causing, peripheral neuropathy increases the likelihood of neuropathy occurrence. In this study geometry optimizations of tigecycline and sulbactam drugs and their combination have been carried out with the evaluation of B3LYP/6-311G (d, p), B3LYP/6-311G (2d, 2p) levels, and the reaction mechanism at semi empirical PM6, which was parameterized for biochemical systems and B3LYP/6-311G (d,p) levels. The main objective of the study is to understand the interaction ofsulbactam with tigecycline, to describe energetic condition of bond formation and electronic structure (orders of the broken and formed bonds). The reaction mechanisms of sulbactam with tigecycline have been studied as stepwise and concerted mechanisms using semi-empircal PM6 and B3LYP/6-311G (d,p) levels.

THEORETICAL STUDIES ON THE REACTION MECHANISM OF HNCS WITH CH2CH RADICAL

2007 ◽  
Vol 06 (01) ◽  
pp. 1-12 ◽  
Author(s):  
JIAN-HUA XU ◽  
LAI-CAI LI ◽  
YAN ZHENG ◽  
JUN-LING LIU ◽  
XIN WANG
Keyword(s):  
Density Functional Theory ◽  
Reaction Mechanism ◽  
Reaction Mechanisms ◽  
Density Functional ◽  
Hydrogen Transfer ◽  
Main Product ◽  
Reaction Pathways ◽  
Theoretical Studies ◽  
Functional Theory ◽  
Ch Radical

The reaction mechanisms of HNCS with CH 2 CH radical have been investigated by density functional theory (DFT). The geometries and harmonic frequencies of the reactants, intermediates, transition states and products have been calculated at the B3LYP/6-311++G(d,p) level. The results show that the reaction is very complicated. Nine possible reaction pathways were identified. The results show that the most feasible reaction channel is the hydrogen-transfer pathway CH 2 CH + HNCS → IMA1 → TSA1 → CH 2 CHH + NCS . The pathway VIC C-S addition channel ( CH 2 CH + HNCS → TSD5 → IMD4 → TSD9 → CH 2 CHS + CNH ) can also occur easily. Ethene and radical NCS is the main product of the studied reaction, and product P8 ( CH 2 CHS and CNH ) may also be observed. Compared with our previous study on the reaction HNCS + CH 2 CH , the present reaction is easier to proceed.

N2 and CO Desorption from Interaction between NO and Nitrogen-Containing Char

2013 ◽  
Vol 860-863 ◽  
pp. 985-988
Author(s):  
Xiu Xia Zhang ◽  
Zhi Jun Zhou ◽  
Jun Hu Zhou ◽  
Ke Fa Cen
Keyword(s):  
Density Functional Theory ◽  
Simulation Study ◽  
Reaction Mechanisms ◽  
Density Functional ◽  
Heterogeneous Reaction ◽  
Reaction Pathways ◽  
Functional Theory ◽  
Exothermic Process ◽  
Axis Parallel ◽  
No Chemisorption

A comprehensive molecular simulation study on heterogeneous reaction mechanisms of NO with nitrogen-containing char is carried out using density functional theory. NO chemisorption and subsequent possible reaction pathways are proposed. Geometries of reactants, products, stable intermediates and transition states are optimized at B3LYP/6-31G(d) level. It is found that NO molecule chemisorption with its bond axis parallel to the edge line of nitrogen-containing char is a weakly exothermic process. The N-O bond in NO molecule tends to dissociate after chemisorption. N2 and CO are desorbed when NO molecules are chemisorbed with the formation of N-N bond. N2 desorption is exothermic, while CO desorption is endothermic. So we conclude that N2 is the dominant product from interaction between NO and nitrogen-containing char.

scholarly journals A computational study of the competing reaction mechanisms of the photo-catalytic reduction of CO2 on anatase(101)

2016 ◽  
Vol 18 (36) ◽  
pp. 25010-25021 ◽  
Author(s):  
Chung Man Ip ◽  
Alessandro Troisi
Keyword(s):  
Carbon Dioxide ◽  
Density Functional Theory ◽  
Reaction Mechanisms ◽  
Density Functional ◽  
Catalytic Reduction ◽  
Computational Study ◽  
Density Functional Theory Calculations ◽  
Reaction Pathways ◽  
Functional Theory ◽  
Reduction Of Co2

Three reaction pathways for the photocatalytic reduction of carbon dioxide to methane are investigated with density functional theory calculations.

scholarly journals Gasification Pathways and Reaction Mechanisms of Primary Alcohols in Supercritical Water

2019 ◽  
Author(s):  
Brian Pinkard ◽  
John Kramlich ◽  
Igor V. Novosselov
Keyword(s):  
Supercritical Water ◽  
Reaction Mechanisms ◽  
Radical Reaction ◽  
Water Environment ◽  
Waste To Energy ◽  
Reaction Pathways ◽  
Free Radical Reaction ◽  
Reaction Products ◽  
Primary Alcohols ◽  
Gaseous Products

<div> <p>Supercritical water gasification is a promising waste-to-energy technology with the ability to convert aqueous and/or heterogeneous organic feedstocks to high-value gaseous products, e.g., green hydrogen. Reaction behavior of complex molecules in supercritical water can be inferred through knowledge of the reaction pathways of model compounds in supercritical water. In this study methanol, ethanol, and isopropyl alcohol are gasified in a continuous supercritical water reactor at temperatures between 500 and 560 °C, and for residence times between 3 and 8 s. <i>In situ</i> Raman spectroscopy is used to rapidly identify and quantify reaction products. The experiments confirm the dominance of chain-branching, free radical reaction mechanisms that are responsible for decomposing primary alcohols in the supercritical water environment. Reaction pathways and mechanisms for three alcohols are proposed, conversion metrics are presented, and results are compared with known reaction mechanisms for methanol and ethanol oxidation.</p> </div> <br>

Sign in / Sign up

Export Citation Format

Share Document